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ConsumerLab.com Answers

Question:I have been having neurological symptoms, and a blood test showed I have toxic levels of vitamin B-6. My multivitamin contains 75 mg of B-6, but this is below the upper limit of 100 mg per day. Could my vitamin contain more than it lists?

Answer: As noted in our B Vitamin Supplements Review, unless you are deficient, you only need to get slightly less than 2 mg of vitamin B6 per day from your diet (including supplements), while the daily upper tolerable intake level (UL) is 100 mg. When you exceed the UL, you start increasing your chances of side effects. [Update: In 2016, the FDA reduced the Daily Value for B-6 to 1.7 mg, but this won't be reflected on most supplement labels until 2018 or 2019.]

Since supplements are required to provide at least 100% of their listed amounts of ingredients at the time you purchase them and, if properly maintained, until a listed expiration date, it is customary and acceptable for companies to put in a bit more (an "overage") than the listed amount of an ingredient to compensate for normal degradation. In fact, according the USP, up to 50% more is permitted for B vitamins.

So, yes, it is possible that your multivitamin provided more than the daily upper limit of vitamin B6 -- putting you at some risk of toxicity. This is because your supplement provided an amount of B6 close to the upper limit (and much more than normally needed) and there is an allowable manufacturing overage, as noted above. However, side effects have generally been reported with daily intakes above 200 mg and, more typically, above 1,000 mg, so it would be unusual for the B6 in your supplement alone (if properly made) to cause the side effects you reported. Foods also contribute B6, but it would also be unusual for any non-fortified food to have put you over the UL since foods naturally rich in B6 (like liver, other meats, potatoes, and bananas) provide about 0.25 to 1 mg of B6 per serving.

Be aware that Europe uses a more conservative daily upper limit (25 mg) than in the U.S.

About 30 years ago, I experienced painful tingling and numbness in my feet and tingling in my spine when I bent my head. I went to many neurologists and a major neurological hospital in New York City, but despite painful tests no one diagnosed the problem. The internet did not exist but one day I read an article in a health magazine which described my symptoms and attributed them to Vitamin B-6 overload. The article even labelled my spine issue Lhermitte's Syndrome, named for a doctor. I had been taking too much B-6 due to the advice of a popular health author of the 80's. I immediately stopped B-6 and months later the symptoms disappeared except for a permanent minor residual numbness and pain in the toes of one foot.

I suffered from a large B6 deficiency. It caused symptoms from temperature regulation to mental function. Something circulating in the blood was compounding it to take it out. Cure was to take 50 to 100 mg/day. Really made a big difference. It seems we don't know much about this vitamin if some people are reporting toxic effects at these levels.

I think the EU, Great Britain and Canada are way ahead of the US, in considering safety issues. I had been taking 100mg of B6 daily, and now take only 25mg. I changed several months ago, when a saw an article on this issue.

Re companies putting in on overage of an ingredient to maintain 100% of the required amount over time: Hard to imagine they feel the need to do this when the expiration date is typically 2 or 3 years after manufacture, similar to what drugs makers list as the shelf life in the original bottle a pharmacist receives. While I know it's not recommended -- and may vary by drug -- I have taken ibuprofen, as well as several blood pressure medicines, more than 5 years past the expiration date, and they were just as effective as they were originally. It would be interesting for CL to test some passing supplements that expired years ago, and see what kinds of results you get re degradation (or not).

I know another patient who had a very similar experience. She was taking a standard B supplement with 100% the daily value of B6, and no other supplements or other products containing B vitamins. She rapidly developed neurological symptoms, which resolved when she switched to taking B1 and B2 supplements without any B6. I would love to gather more reports of this response -- I suspect that there may be some people who are hypersensitive to B6, or who have a variation in B6 metabolism that allows them to reach toxic levels at "normal" supplement doses.

I agree that this would be unusual; the question is whether it's impossible (barring a manufacturing error, as you noted), or whether there's a small subset of people who are hypersensitive to B6 supplementation. If such people do exist, it would be important for doctors and consumers to know that they shouldn't categorically rule out normal levels of B6 supplementation as a possible cause of neurological symptoms.

I had a similar experience. My B-Complex only had 50mg of B6, but when my PCP tested by B6 levels, they were 5x what they should have been. He told me to immediately stop my supplement - permanent damage can occur if the B6 levels are too high for too long. I stopped the supplement and my symptoms resolved over time.